This invention relates to new flame retardant polyester compositions. More particularly, this invention relates to new flame retardant copolyesters and to a method for producing the copolyester compositions. More particularly this invention relates to new flame retardant copolyesters produced from terephthalic acid, another dicarboxylate moiety and carboxy-phosphinic acids, a process for producing the copolyesters and shaped articles produced from the copolyesters.